Category Archives: Radio history

1948 Permeability Tuned Receiver

1948JanPS1Even though the war was over, it appears that aluminum was still in somewhat short supply, or at least expensive, in 1948, since it’s not unusual to see radios from that era using permeability tuning, which means that a variable capacitor was not required.

1948JanPS2Here’s one such example from the January 1948 issue of Popular Science. This little one-tube set uses a 12BA6 as a regenerative detector, with a 35W4 rectifier and “curtain burner” cord to run the filaments.  Tuning is accomplished by moving a slug through the coil, changing the inductance.  The complete coil assembly was  available as a commercial part, and was listed on the parts list as merely a “permeability tuning unit for regenerative circuit.”

The accompanying article didn’t include an explanation for hooking up the dial string, since the entire assembly was commercially available, and the other parts were simply squeezed in.

Eunice Johnson, KOA Denver

1928JanRadioDigestShown here on the cover of the January 1928 issue of Radio Digest is Eunice Johnson of KOA Denver, described as “the most beautiful artist” in radio.  According to the magazine, she was “still in her teens, but she sings and talks to her audience like an old timer.”

The GE station signed on in 1924 with 5000 watts, increasing to 12,500 watts in 1927.  It went to its current power of 50,000 watts in 1934.

1938 Two-Tube Regenerative Receiver

1938JanSWTV11938JanSWTV2Eighty years ago, the January 1938 issue of Shortwave and Television magazine carried the plans for this two-tube regenerative shortwave receiver.  With plug-in coils, the set would cover 550 through 9 meters. The set used two 1.5 volt tubes: The RK42 triode served as regenerative detector, and a dual RK43 provided two stages of audio amplification.

The set was capable of pulling in stations from around the world, and “there is practically no limit to which this receiver will cover. So long as general receiving conditions are favorable, this little set will work wonders.”

The use of two variable capacitors allowed for bandspread tuning, and a variable resistor was used for regeneration.


1943 Coil Winding Tip

1943JanRadioCraft75 years ago this month, the January 1943 issue of Radio Craft carried this hint for winding coils.

The idea was sent in by one Tony Calabrese of White Plains, NY, and was billed as a good method for anyone to get a professional looking coil.

One end of a designated length of wire was attached to the wall or some other fixed object, with the other end attached to the coil form. After a couple of turns, the weight was placed on the wire to maintain tension.

When the coil was complete, the weight was slipped off, resulting in a neat coil with evenly spaced turns.

GE Shortwave Stations, 1943

1943Jan11LifeThis full-page ad by GE appeared inside the front cover of Life magazine 75 years ago today, January 11, 1943, and told the importance of the GE shortwave stations, KGEI, WGEO, and WGEA.  In addition to being a link to home for the armed forces, the stations broadcast “from a free people to men with freedom in the hearts” in Asia and Europe.

1967 Homemade Electronic Bug


Fifty years ago this month, the January 1968 issue of Electronics Illustrated offered just the thing for aspiring spooks, namely, this homemade electronic bug. Housed in the ubiquitous cigarette pack, the tiny device transmitted on the AM band, and could be picked up 10-50 feet away.

It was billed as suitable for listening in on “your neighbor, close friend, worst enemy, bookie, business partner, the business competition, or even you.”

As shown here, the parts had a price tag of about $20, although the article noted that the price might be lower if slightly larger components would be acceptable.

The circuit used four Motorola transistors, three 2N4123’s and one MPS3646 handling the RF output duties. It was constructed on a circuit board with holes drilled for the components, with wiring on the other side.

The battery shown here is a Burgess H-177 9.8 volt battery, although the article pointed out that a standard 9 volt battery could be used if the slightly larger size were acceptable.

1918 Ground Current Telegraph

1918JanPS1With civilian radio (both transmitting and receiving) shut down for the duration of the war, hams a hundred years ago still had a desire to engage in communications. As we’ve seen prevsiously (here, here, here and here), one method of communicating without the use of radio waves is a ground-conduction telegraph. And a hundred years ago this month, the January 1918 issue of Popular Science showed how to do it.

The magazine noted that “because the Government, for good and sufficient reasons, has put a ban on amateur wireless stations, it does not follow that all your activities must stop.” It noted that communicating by ground wireless was “almost as interesting” as actual radio and was “permitted by the Government, since high tension apparatus need not be used, at least not in their normal capacities.”

While the magazine noted that the Allies were apparently not using this type of communication, “for all we know the Germans may be using it now,” and that it had a potential range of forty miles, and perhaps more through salt water.  (The 40 mile estimate seems extremely optimistic, but I can’t say I’ve ever tried it.)

1918JanPS2In addition to the basic circuit shown above, the magazine also showed this more advanced setup, which permitted full break-in operation (with the addition of a normally-closed contact to the key).  It looks just slightly dangerous, and would probably trip a modern ground fault interrupter.  It doesn’t appear to send any signal over the power lines, but does use the electric service ground as one of the two connections.

Blaupunkt Palma 2435 (1957)

1957BlapShown here is Gerti Daub, Miss Germany 1957, along with two other avid SWL’s, tuning in a program on their Blaupunkt Palma 2435 receiver.

The seven-tube set retailed for 390 Deutschmarks, and tuned both the longwave and mediumwave broadcast bands, FM (up to 100 MHz), and  shortwave.  You can see the set in action at this video:



My First Radio Receiver by V. Borisov

SovietMyFirstRadioThe young comrades shown here are constructing their first radio receiver, according to plans contained in the 1955 Soviet book, Мой первый радиоприёмник (My First Radio Receiver), by V. Borisov , part of the series Библиотека юного конструктора (Library of the young designer), a series of small books published between 1937 and 1964 showing various construction projects, many related to radio.

SovietMyFirstRadioCrystalSet1The first set in the book, shown here, is not immediately recognizable, but it is a simple crystal set, with a tuning range of 200 to 2000 meters (150 – 1500 kHz), to cover the longwave and mediumwave broadcast bands.

The largest component is the dual coil, which appears to be a manufactured part.  The two binding posts on the left are for the antenna (A) and ground (3).  The knob in the center is a switch for selecting taps on the coil.  The actual detector is not shown.  It plugs into the terminals at the top right of the top drawing.  The headphones plug in to the other set of terminals.

The detector, shown below is a manufacture fixed detector.


The book’s second crystal set, shown below, is slightly more advanced, and is shown below.  This set also uses the same fixed crystal, and includes a variometer, which also appears to be a manufactured unit that the builder purchases.


The final crystal set is shown below.  It uses the same fixed detector, and includes a variable capacitor for tuning.  The fixed coil in this one appears to be much simpler than the ones employed in the other set, but there don’t appear to be any instructions for winding it.  So I assume that this is also an item that the builder simply purchases.


SovietMyFirstRadioTubeSetAfter showing these crystal set designs, the book moves on to some simple vacuum tube receivers.  The basic one-tube receiver is shown at left.  Since I can’t read much of the text, it’s a little unclear exactly which circuit is shown here.  The text includes a number of different schematics, along with different pictorial diagrams for the tube socket.  I assume this is because different builders might get their hands on different tubes, and the diagrams are shown for various common tube types.  A representative example is shown below, the circuit diagram for use with a 1Б1П tube.

SovietMyFirstRadio1b1pSince B batteries might be hard to come by for struggling soviet radio builders, the book also includes plans for a power supply, using a transformer and 5Ц4С dual rectifier (the equivalent of a Western 5Z4G).

The book also contains plans (but unfortunately, no picture of the completed set) for a two-tube regenerative receiver with one stage of audio amplification to drive the speaker.  This set is presented after the rather complex power supply is shown, so I assume it’s a project for the advanced student.

The book shows how to set up an antenna, and shows diagrams of nice outdoor antennas, complete with lightning switches, passthroughs to get them into the house, and grounds.  But for those who didn’t want to go to all that bother, it also shows the self-explanatory method shown below for using the house wiring as an antenna.  The same idea was featured on this side of the iron curtain, as can be seen at this post.  Both great minds had the same idea:  Connect a radio to the house wiring, using a capacitor to let the RF through, but keep the high voltage out.  It’s a great idea unless the capacitor develops a short, in which case the headphones on your head suddenly become energized with the household current.


Many an American kid got his start in radio when he discovered Alfred Morgan’s book in the elementary school library.  I wouldn’t be surprised if there were Soviet kids who did just the same thing when they discovered Borisov’s book.

This book, and thousands of other old Soviet books and magazines, can be found at can be found at Журналы СССР.  Even if you can’t read the text, the site is worth exploring.

1928 Homemade Fuses

1928JanPMIf you need a fuse but the store is closed, then you can just make your own the way they did it 90 years ago, as shown in the January 1928 issue of Popular Mechanics.

The exact current values are not shown, but the accompanying article describes the use of the fuse on a radio. The fuse itself is made of tinfoil from a gum or candy wrapper. For the A battery, the article called for a strip 1/16 inch thick. For the B battery, which would use less current, it called for a strip 1/32 inch wide.

The idea had been submitted to the magazine by one R.J. Williams of Chicago.